Download Map-ity Free Unity. 

Map-ity allows you to use any real-world locations by providing access to Open Street Map data.

Links:Website | User Manual | Documentation | Forum | Videos
Use it to get a lists of roads, waterways and buildings to use in your scene! You can even break down the data into different classifications such as:
– Motorway (primrary or secondary road)
– Canal or river

Compatible with WorldComposer.
Compatible with BuildR – Building Generator. – Sample package included.
Compatible with SuperSplines